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Progress in DoNuTS Pelletron Retrofit Operations

Charles YeamansDomestic Nuclear Threat Security Initiative technical meetingSeptember 16, 2009

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Why there is a lot of cursing and a burning smell coming from the basement of Etcheverry Hall but

Professor Morse is upstairs.

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Outline

1. Pelletron basics2. Timeline, tasks completed3. Ongoing tasks4. Future tasks and requirements

• --Photos by Matt Pistone

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Current ProjectCurrent Project

• 3.5 MeV Pelletron electron accelerator3.5 MeV Pelletron electron accelerator

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A Pelletron is a Van de Graaff-type accelerator with a chain of discrete steel pellets connected by insulating Teflon linkages instead of a continuous belt.

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Voltage is supplied to the terminal by rotating the pellet chains through an inductor/suppressor electrode pair that is biased by a 60 keV commercial high voltage source.

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The terminal consists of an inductor/suppressor pair for the high-voltage end of the charging system, an electron source*, focusing and steering components*, and control electronics*.

*not pictured7

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The electron beam is accelerated in a tube consisting of a series of ceramic rings, connected with 370 M resistors placed across the spark gaps to create a linear acceleration potential.

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The chains, chain motors, high-voltage terminal, and other hardware are contained in a pressure tank. Pressurizing the tank to 80 psi with SF6 allows the terminal to be run at the full rated voltage.

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Pelletron timeline, 2008:

June-August: Major cleanout operations in 1140 Etcheverry create space for new experiments, specifically the Pelletron.

September: Pelletron pressure tank and ~70 tons of its closest friends arrive in Berkeley. Everything is stored in 1140.

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Pelletron timeline, 2009:

January: Tank is lifted into its current position on concrete piers by Morse, Mozin, Quiter.

March: Yeamans hired, more cleaning

April: SF6 arrives, task completed: taking delivery of the Pelletroncontinued lab cleaning and organization

May-June: Undergraduate trainees begin their training by cleaning the lab, task completed: 1140 Etcheverry clean enough to be functional

July: New beam tube arrives

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July, 2009: The new beam tube arrives.

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Pelletron timeline, 2009:

• July 22-24, 2009: 1st Workshop on Special Topics in Homeland Nuclear Security

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Undergrads effectively staffed the event.

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Prof. Morse represented the DoNuTS Initiative in the plenary session and entertained various dignitaries.

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The poster session was enlightening.

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There was much discussion.

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A lab tour concluded the workshop.

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A lab tour concluded the workshop.

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A lab tour concluded the workshop.

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A lab tour concluded the workshop.

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A lab tour concluded the workshop.

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Pelletron timeline, 2009:

July 27-31: Fun stuff

• tandem terminal disassembled and removed

• Former low-energy acceleration tube removed from tank

• New electron acceleration tube inserted into tank

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Pelletron timeline, 2009:Completed task: New electron acceleration tube inserted into tank

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New DoNuTS Website

25Completed, though can take content updates as available.

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Ongoing Tasks

1. beamline assembly

2. terminal retrofit

3. shielding design and dose calculation

4. interlock

5. licensing and regulatory compliance

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Ongoing Tasks:beamline assembly

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Beamline assembly: reactor room

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Beamline assembly: current configuration

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Beamline assembly: current configuration

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Beamline assembly: proposed alignment

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Beamline assembly: proposed alignment

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Ongoing Tasks:terminal retrofit

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Ongoing Tasks:terminal retrofit

The tandem stripper terminal has been disassembled. As soon as components arrive from NEC, the new electron gun terminal can be assembled.

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Ongoing Tasks:shielding design and dose calculations

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Dose calculations must be done on proposed beamline alignment and shielding.

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Ongoing Tasks:interlock

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The interlock is being built to the current industry standard and will need to withstand a thorough independent design review and functional testing.

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Ongoing Tasks:licensing and regulatory compliance

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Ongoing Tasks: regulatory compliance

• The accelerator must be licensed by the state of California, per NRC agreement.

• UC Berkeley campus RSO ultimately submits the application, so he gets the last word on safety-related design elements.

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Future Tasks

0. Shielding design and calculations

1. Accelerator and beam control system

2. Beam line assembly

3. Target3a.Bremsstrahlung end station

3x.Hair of the Dog

4. Detectors and data acquisition

5. Detector characterization41

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Future tasks: Shielding

0. Shielding Calculations (V. Mozin)– 6 months– Required: Monte Carlo calculations of

radiation shielding for accelerator licensing and finalizing accelerator footprint.

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Future tasks: Control System

1. Accelerator / Beam control system– 2 gs-years (1 year – rough system, 1 year

refinement)– Required: Design interface for all accelerator

control systems, and write control software and basic GUI for all accelerator operations. This is currently being done by CBY and he can continue to do so to until September 2010 or until he is offered a better position.

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Future tasks: Beam Line

2. Beam Line Assembly– 2 gs-years (1 year – assembly / calculations, 1 year –

calibration), though may be concurrent with Accelerator/Beam control period if done by a competent and motivated individual. CBY time on procurement and assembly counts as 2.5x gs time, all other tasks 1.0x.

– Required: Do calculations for electron beam optics to determine optimal operating conditions, calibrate Pelletron HV signal and bending magnet settings, and perform beam line hardware procurement and installations as needed.

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Future tasks: Beam Line (2)

2. Beam Line Assembly: Hardware

– On order: electron gun, getter pump and valve, X-Y steerer and solenoids, voltage controller, larger fiber optic chassis

– Necessary electronics, not yet ordered• Electron gun driver and controller• Terminal electronics box

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Future tasks: Target

3a. Bremsstrahlung end station– 3-6 months with decent undergrad hours

available, largely fabrication and assembly– Required: Design and build bremsstrahlung

radiator, make stands for W/Pb & detector assemblies, assemble W/Pb detector house.

3b. Hair of the Dog– resonant photon generation through resonance

excitation and mechanical Doppler compensation

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Future tasks: Detectors/DAq

4. Detector Electronics & Data Acquisition System– 3 gs-years (1 year – electronics, 1 year – acquisition

system, 1 year - testing)– Required: Design, implement, and build detector

electronics and data acquisition system for event-by-event acquisition from up to 8 HPGe detectors. May be optimal to duplicate a sub-set of the STARS/Liberace electronics/acquisition system and/or re-use components of the PFNA system.

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Future tasks: Detector Characterization

5. Detector Characterization– 3 gs-years– Required: Perform Monte Carlo calculations

and experiments to fully characterize HPGe dectector array. This includes shielding optimization. Benchmark against Angell/Norman results and then expand.

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Future Work…

Q: When will the Pelletron be operational so I can walk in and use it for NRF or other experiments?

A1: The probability of the date of first operation is approximately lognormal, starting at May 2010 and having the mode around September 2010.

A2: The line forms behind Ed Morse and Rick Norman.

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questions/comments

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